As a working rule for design, an open gym floor holds about one person per 5 sqm, a group training studio about one person per 3 sqm during a class, and a Pilates or reformer studio is limited by equipment spacing at roughly one person per 4.5 to 6 sqm. In Australia these numbers sit alongside a regulatory occupant density of one person per 3 sqm applied to activity areas of an assembly building, which governs egress, ventilation and amenities rather than how many members you should actually put on the floor. The number that matters for your business is usually lower than the number the code allows, because comfort, equipment access and member experience run out well before the fire exits do.

This guide separates the two questions founders confuse: the legal maximum (occupant load, set by codes) and the usable capacity (how many members can train well at once). Get both right before you commit to a space. If you are still choosing a site, our gym lease guide and the free 2D and 3D design service let you test capacity against a real floor plate before you sign.

The two capacity numbers every founder needs

Capacity is not one figure. It is two, and they answer different questions.

• Occupant load (the legal maximum): a code-driven number that sizes exits, doors, ventilation and toilets. In Australia, gyms are almost always classified as assembly buildings. Under the National Construction Code, authorities consistently lean toward Class 9b for any facility involving exercise or sport, regardless of scale.
• Usable capacity (the business number): how many members can train comfortably and safely at the same time. This drives your class sizes, peak-hour experience and revenue model, and it is almost always lower than the legal maximum.

Confusing the two is how founders end up with a floor that looks full at 40 people but is legally rated for 100, or a studio that passes certification but feels cramped in every class.

Occupant density by model: the reference numbers

Australian mechanical engineers design gym ventilation around well-established occupancy densities. Design occupancy density for gym floors is typically 1 person per 5 sqm, and group fitness studios may be 1 person per 3 sqm during classes. On the regulatory side, the NCC applies an area-per-person factor of 3 sqm per person to a gymnasium activity or floor area when calculating how many people a space is deemed to accommodate.

International codes take a similar shape, which is useful for sense-checking. Under widely used North American life safety codes, exercise rooms with equipment are calculated at about 50 square feet per person (roughly 4.6 sqm), while rooms without equipment use a denser 15 square feet per person (about 1.4 sqm). The pattern is consistent: equipment-heavy floors need more space per person, open studio floors need less.

These are planning rules of thumb for usable capacity, not a substitute for a certified occupant load calculation. Confirm the legal figure with your building certifier and council.

How to do the maths

The core formula is simple: divide your usable floor area by the area you allocate per person.

• Step 1: Take the net activity area, not the gross lease area. Subtract change rooms, reception, offices, corridors, storage and plant.
• Step 2: Divide by your per-person figure for that zone. For an open gym floor at 5 sqm per person, a 250 sqm net floor holds about 50 people at once.
• Step 3: Do it zone by zone and add the totals, because a mixed facility has different densities in each room. Add the reformer studio, the strength floor and the class space separately.

A worked example: a 300 sqm site with 60 sqm of amenities and back of house leaves 240 sqm of activity area. As an open floor at 5 sqm per person that is roughly 48 members training at peak. Split it into a 150 sqm strength floor (about 30 people) plus a 90 sqm class studio running at 3 sqm per person (about 30 per class) and you can serve more members across the day, but only if your timetable staggers demand.

Why the legal maximum is higher than what you should plan for

Codes exist to get people out safely, not to guarantee a good workout. A room can be legally rated for far more people than can realistically train there. In one commonly cited case, applying the standard exercise factor produced an occupant load of around 450 people for a facility that had never had over 100 occupants and only had parking for 100 vehicles. The lesson for founders: plan around usable capacity, then confirm the legal occupant load separately for egress, amenities and certification.

There is also a classification tripwire. In several building codes, once occupant load crosses a threshold, a space is treated as a higher-risk assembly use, which can trigger panic hardware on doors and affect plumbing fixture counts. Design decisions that push your rated occupancy up can quietly add compliance cost, so it pays to model this early.

Ventilation and amenities scale with people, not floor size

Capacity is not just floor space. It drives your mechanical services and your toilets. Under AS 1668.2, exercise areas need 10 L/s of outdoor air per person, and a person exercising generates 400 to 600 watts of metabolic heat compared with about 120 watts for a seated office worker. That is why gyms are one of the most demanding HVAC applications in commercial fit-out. Pack more people per square metre, in a spin or HIIT studio for example, and your cooling and fresh-air loads climb sharply. Amenities scale the same way, so a higher rated occupancy can mean more toilets and showers. These are exactly the trade-offs a proper fit-out and layout plan should resolve before construction.

Layout implications: designing for capacity that feels right

Usable capacity is won or lost in the layout. A few principles that consistently matter:

• Circulation is not wasted space. Aisles and clear zones around equipment are what let your rated capacity actually train at once. Squeeze them and real capacity falls even if the number on paper does not.
• Zone by intensity and noise. Placing a free-weights area next to a quiet studio with no acoustic separation generates complaints from day one, so map adjacencies before fixing wall positions.
• Reformer and rig spacing sets your ceiling. In equipment-defined studios, capacity is the number of machines that fit with safe clearances, not a density formula.
• Design for peak, run for average. Your busiest hour, not your average, dictates whether members feel crowded. Staggered timetables let a modest floor serve a large membership base.

This is where a scaled plan earns its keep. VERVE's free 2D and 3D gym design service lets you see how many stations, reformers or class spots genuinely fit a specific floor plate, so capacity is a design decision rather than a guess.

What capacity means for cost and timeline

Your capacity model shapes your budget, because more stations and denser studios mean more equipment and services. Based on VERVE's published fit-out data (real delivered projects over the twelve months to July 2026), median equipment spend is about $27,500 ex GST and the average is just over $40,000, while full builds typically run $50,000 to $200,000 for 150 to 400 sqm, or about $300 to $600 per sqm. On timelines, that same data shows founder projects moving from first design to deposit in 3 to 10 weeks, and from signed lease to open doors in 8 to 16 weeks. For the full picture, see our guides on the cost to open a gym and the fit-out timeline.

Capacity also feeds directly into your revenue model. Knowing how many members you can serve at peak, and how many classes per week your studio can run, is the input for your break-even and cash flow plan. You can pressure-test the numbers with the free founder planning tools.

Regulatory reality check

Occupant load, egress, accessibility and amenities are governed by the NCC and enforced through your council and building certifier, and requirements vary by state and by site. The figures in this article are planning guidance, not compliance advice. Confirm your certified occupant load, exit provisions and sanitary facility counts with your building certifier and council before you commit. For the approvals side, start with our guide to council approval for a gym and the broader how to open a gym in Australia guide. For finance and lease decisions tied to your capacity plan, speak to your broker, accountant or lawyer.